Process for treatment of substrates with water vapor or steam

ABSTRACT

A method of treating a substrate comprises, in one aspect, placing a substrate having material on a surface thereof in a treatment chamber; directing a stream of a liquid treatment composition to impinge the substrate surface; and directing a stream of water vapor to impinge the substrate surface and/or to impinge the liquid treatment composition. A preferred aspect of this invention is the removal of materials, and preferably photoresist, from a substrate, wherein the treatment composition is a liquid sulfuric acid composition comprising sulfuric acid and/or its desiccating species and precursors. In another aspect, a liquid sulfuric acid composition comprising sulfuric acid and/or its desiccating species and precursors are dispensed onto a portion of the substrate surface that is less than the entire surface of the substrate in an amount effective to treat the portion of the substrate surface, and the liquid sulfuric acid composition is exposed to water vapor in an amount effective to increase the temperature of the liquid sulfuric acid composition above the temperature of the liquid sulfuric acid composition prior to exposure to the water vapor. The substrate may be enveloped with a water vapor and/or an optionally nitrogen gas environment during the treatment steps.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Nonprovisional applicationSer. No. 12/152,641, filed May 15, 2008, entitled “PROCESS FOR TREATMENTOF SUBSTRATES WITH WATER VAPOR OR STEAM”, which claims the benefit ofU.S. Provisional Application Ser. No. 60/930,720, filed May 18, 2007,entitled “PROCESS FOR TREATMENT OF SUBSTRATES WITH WATER VAPOR ORSTEAM”, which applications are incorporated herein by reference in theirentirety.

FIELD OF THE INVENTION

The present invention relates to methods for treatment of substrateswith water vapor or steam. In an aspect of the present invention,material (and preferably photoresist materials) is removed fromsubstrates using sulfuric acid and water vapor.

BACKGROUND OF THE INVENTION

Advances in electronic technology cause integrated circuits to be formedon substrates such as silicon wafers with ever increasing packingdensity of active components. The formation of circuits is carried outby sequential application, processing, and selective removal of variouscomponents from the substrate. Various compositions have been developedfor removal of specific classes of components from substrates insemiconductor wafer technologies. For example, a composition commonlydenoted SC-1, which contains a mixture of NH₄OH(29 wt %)/H₂O₂(30 wt%)/water at a volume ratio of about 1:1:5 (or at somewhat higherdilution ratios), is typically used to remove particles and to reoxidizehydrophobic silicon surfaces. Similarly, a composition commonly denotedSC-2, which contains a mixture of HCl (37 wt %)/H₂O₂(30 wt %)/water at avolume ratio of about 1:1:5 (or at somewhat higher dilution ratios), istypically used to remove metals. An additional composition, commonlycalled a Piranha composition, comprises H₂SO₄(98 wt %)/H₂O₂(30 wt %) ata volume ratio of about 2:1 to 20:1, and is typically used to removeorganic contamination or some metal layers.

Photoresist materials are used in many circuit manufacturing processesto assist in formation of sequential layers. In stages of themanufacturing process, these photoresist materials are often removed,preferably without substantial damage to the substrate, includingstructures formed thereon. Photoresists are conventionally removed usingorganic solvents, such as n-methyl-pyrrolidone (“NMP”), glycol ether,amine, or dimethyl sulfoxide (“DMSO”). Alternatively, photoresistmaterials have been removed using inorganic chemical agents such assulfuric acid and hydrogen peroxide, or using reactive gaseous chemicalsgenerally known as photoresist plasma ashing. U.S. Pat. No. 5,785,875discloses a method for removing photoresist material by carrying out awet acid etch by fully submerging the wafers within anhydrous acid, anddraining the etching agent from the chamber while inserting a heatedsolvent vapor. The solvent is, for example, acetone, alcohols, oranother solvent, but preferably comprises isopropyl alcohol, and isheated to the range of between about 50° C. and about 100° C.Traditional wet chemical processes used to remove photoresist rely onconcentrated sulfuric acid combined with hydrogen peroxide (Piranha or“Sulfuric-Peroxide Mix” or SPM) or ozone (sulfuric-ozone mix or “SOM”).Alternatively, photoresists can be removed under certain conditions byusing ozone dissolved in DI water or by mixing ozone gas with watervapor at elevated temperatures.

Particularly challenging is the removal of patterned photoresist thathas been subjected to ion implantation processes, which cause hardeningof the resist surface. An approach to removing this implantedphotoresist is to increase the temperature of the chemical treatment.Additionally, removal of dopants that are applied to substrates byplasma doping can be very difficult. U.S. Patent Publication No.2007/0243700 describes a technique whereby the dopant-containing layeris stated to be removed from the photoresist layer by exposing thedopant-containing layer to a water rinse, a chlorinated plasma or to afluorinated plasma.

It would be desirable to identify alternative techniques andcompositions for treatment of substrates, particularly to removematerials, especially organic materials, and most especially photoresistmaterials from substrates such as semiconductor wafers.

SUMMARY OF THE INVENTION

Applying hot chemicals to substrates is challenging, because heating thechemicals presents concerns in safety, in the effectiveness of thechemicals, and in durability of the equipment used to contain and handlethe chemicals. As for safety, the handling of potentially harsh,caustic, and aggressive liquid or gaseous chemicals alone raises certainconcerns. Heating these materials to high temperatures only compoundsthe concerns because the materials are more volatile and prone toescaping in larger amounts into the atmosphere. Additionally, certaintreatment chemicals degrade or are less effective over time due toundesired or inadvertent reactions that are promoted at a highertemperature. Finally, treatment chemicals tend to have an even higheradverse effect on vessels, tubing, valves, pumps, etc. when they areprovided in the system at a higher temperature. It is desirable toprovide treatment chemicals with high energy associated with heat at ornear the time of contact with the substrate to be treated.

In one aspect of the present invention, a method of treating a substrateis provided, comprising a) placing a substrate having material on asurface thereof in a treatment chamber; b) directing a stream of aliquid treatment composition to impinge the substrate surface; and c)directing a stream of water vapor to impinge the substrate surfaceand/or to impinge the liquid treatment composition. Preferably, thestream of water vapor is in the form of steam.

Because energy is provided in the form of the steam of water vapor, thetreatment composition does not need to be pre-heated to as high a levelprior to dispensing onto a substrate as previously required. In apreferred embodiment, the treatment composition interacts with the watervapor to provide an enhanced benefit of treatment activity. In thisembodiment, provision of the stream of water vapor in a manner thatimpinges the substrate surface and/or to impinge the liquid treatmentcomposition provides more effective dispensing of the water vapor whereit is needed, rather than merely providing a water vapor in the chamberin the hope that enough water vapor is present to accomplish the desiredenhancement of benefit of the treatment activity.

Additionally, because heat and/or interaction of the water vapor withthe treatment composition is so effective at the surface of thesubstrate to be treated, significant efficiencies can be observed in thetime required for actual treatment of the substrate. In particular,substantial reduction in treatment time may be observed in the removalof photoresist materials using a modified SPM process as describedherein.

Examples of treatment compositions that can be used in the presentinvention include wafer cleaning systems that are conventional in theart, such as the SC-1 composition (NH₄OH/Peroxide/Water), the SC-2composition (HCl/Peroxide/Water), the Piranha or SPM composition(Sulfuric Acid/Peroxide), SOM (sulfuric acid/ozone) compositions,sulfuric acid compositions, buffered oxide etch (HF and ammoniumfluoride) compositions, and NH₄OH, H₃PO₄, HF, HCl or HF/HClcompositions.

A preferred treatment of the present invention is the removal ofmaterial, and particularly of photoresist material. As noted above,sulfuric acid/peroxide mixtures have been used in wet chemicalprocesses. It has been determined that applying sulfuric acid and/or itsdesiccating species and precursors (e.g. sulfur trioxide (SO₃),thiosulfuric acid (H₂S₂O₃), peroxosulfuric acid (H₂SO₅),peroxydisulfuric acid (H₂S₂O₈), fluorosulfuric acid (HSO₃F), andchlorosulfuric acid (HSO₃Cl)) to photoresist coated substrates in animmersion bath environment, even at elevated temperature, is noteffective in removal of harshly treated photoresist. In view of this ithas surprisingly been found that sulfuric acid and desiccating sulfuricacid species and precursors can be effective in removing materials,especially organic materials and most especially photoresist materialsfrom the surface of substrates using certain advantageous treatmenttechniques.

In one aspect of the present invention, a method of removing materialfrom a substrate is provided, comprising a) placing at least onesubstrate having material on a surface thereof in a treatment chamber;b) directing a stream of a liquid sulfuric acid composition comprisingsulfuric acid and/or its desiccating species and precursors to impingethe substrate surface; and c) directing a stream of water vapor toimpinge the substrate surface and/or to impinge the liquid sulfuric acidcomposition. Preferably, the liquid sulfuric acid composition has awater/sulfuric acid molar ratio of no greater than about 5:1, and isexposed to water vapor in an amount effective to increase thetemperature of the liquid sulfuric acid composition above thetemperature of the liquid sulfuric acid composition prior to exposure tothe water vapor.

By directing both the stream of liquid sulfuric acid composition and thestream of water vapor in the manner described, effective mixing of thesecomponents at or near the surface of the substrate is accomplished, withsurprisingly effective stripping rates being achieved.

In another aspect of the present invention, a method of removingmaterial from a substrate is provided, comprising a) placing at leastone substrate having material on a surface thereof in a treatmentchamber; b) dispensing a liquid sulfuric acid composition comprisingsulfuric acid and/or its desiccating species and precursors onto aportion of the substrate surface that is less than the entire surface ofthe substrate in an amount effective to treat the portion of thesubstrate surface; and c) exposing the liquid sulfuric acid compositionto water vapor in an amount effective to increase the temperature of theliquid sulfuric acid composition above the temperature of the liquidsulfuric acid composition prior to exposure to the water vapor; whereinthe liquid sulfuric acid composition at the time of exposure to watervapor has a water/sulfuric acid molar ratio of no greater than about5:1.

It has been found that selective dispensing of the liquid sulfuric acidcomposition onto a portion of the substrate surface that is less thanthe entire surface of the substrate is advantageous in certainapplications. By controlling the dispense of the liquid sulfuric acidcomposition in this manner, portions of the substrate in greater needfor treatment can be selectively treated.

In an embodiment of the present invention, the liquid sulfuric acidcomposition is exposed to water vapor in an amount effective to increasethe temperature of the liquid sulfuric acid composition above both (i)the temperature of the liquid sulfuric acid composition prior toexposure to the water vapor and (ii) the temperature of the water vapor.In a preferred embodiment, a liquid sulfuric acid composition having awater/sulfuric acid molar ratio of no greater than about 5:1 is exposedto water vapor in an amount effective to increase the temperature of theliquid sulfuric acid composition on the substrate surface above both (i)the on-substrate temperature of the liquid sulfuric acid compositionprior to exposure to the water vapor and (ii) the temperature of thewater vapor. The present method is particularly significant in the caseof removal of photoresist materials, even in the case when thephotoresist is baked onto the substrate or when the photoresist isheavily ion implanted, under certain process conditions.

In an embodiment of the present invention, it has been discovered thatthe oxidizing agent of acidic or basic treatment compositionstraditionally useful in silicon wafer treatment can advantageously notbe present in the acidic or basic composition when stored or preparedfor use in the treatment method, but can be added to the treatmentcomposition immediately prior to dispensing on the substrate, can beintroduced with the water vapor at or near the surface of the substrateto be treated, or can be introduced as a separate component at or nearthe surface of the substrate to be treated. As a specifically preferredexample, the peroxide or the ozone in sulfuric acid compositions knownas SPM and SOM compositions can be advantageously added to the sulfuricacid composition in the dispense line between the supply reservoir andthe dispense nozzle. In another embodiment, the oxidizing agent can beintroduced with the water vapor rather than the sulfuric acidcomposition at or near the surface of the substrate to be treated. Inanother embodiment, the oxidizing agent can be dispensed as a separatecomponent from both the sulfuric acid composition component and thewater vapor component. While not being bound by theory, it is believedthat separation of the oxidizing component from the acid or basecomposition provides advantages in stability and effectiveness.

In an aspect of the present invention, a method of treating a substrateis provided, comprising a) placing a substrate having material on asurface thereof in a treatment chamber; b) directing a stream of aliquid treatment composition to impinge the substrate surface; c)directing a stream of water vapor to impinge the substrate surfaceand/or to impinge the liquid treatment composition, and d) additionallyintroducing water vapor and/or nitrogen gas into the treatment chamberto envelop the substrate with a water vapor and/or a nitrogen gasenvironment during the treatment steps b) and c).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph showing the resulting temperature rise when liquidwater or H₂O₂ (30 wt %) is added to H₂SO₄ (96 Wt %).

FIG. 2 is a graph showing the temperature rise when liquid water isadded to a blend of H₂SO₄ (96 Wt %)/water as a function of the fractionof H₂SO₄ (96 Wt %) in the solution.

FIG. 3 is a schematic diagram of an apparatus that can carry out anembodiment of the process of the present invention.

FIG. 4 is a cross sectional view of a spray bar for carrying out anembodiment of the process of the present invention.

FIG. 5 is a schematic diagram of an apparatus that can carry out anembodiment of the process of the present invention.

FIG. 6 is a graph showing experimental oxide etch results of trials withand without the use of methodologies of the present invention.

FIG. 7 is a graph showing wafer temperatures achieved by dispensing thesulfuric acid composition at the same temperature, but under differentconditions of co-disperse with water vapor.

DETAILED DESCRIPTION

The above mentioned and other advantages of the present invention, andthe manner of attaining them will become more apparent, and theinvention itself will be better understood by reference to the followingdescription of the embodiments of the invention taken in conjunctionwith the accompanying drawings.

For purposes of brevity, liquid sulfuric acid compositions as discussedherein will be understood to comprise sulfuric acid and/or itsdesiccating sulfuric acid species and precursors, and discussionsregarding sulfuric acid contained in these liquid compositions willlikewise be understood to describe corresponding compositions comprisingsulfuric acid and/or its desiccating sulfuric acid species andprecursors. Examples of desiccating sulfuric acid species and precursorsof sulfuric acid include sulfur trioxide (SO₃), thiosulfuric acid(H₂S₂O₃), peroxosulfuric acid (H₂SO₅), peroxydisulfuric acid (H₂S₂O₈),fluorosulfuric acid (HSO₃F), and chlorosulfuric acid (HSO₃Cl). In anembodiment of the present invention, a desiccating species of sulfuricacid is a complex of sulfuric acid with an oxidizing agent. For purposesof the present invention, the water/sulfuric acid molar ratio iscalculated for compositions comprising the desiccating sulfuric acidspecies and precursors based on the molar ratio in the final mixture ofwater to the moles present of the desiccating sulfuric acid species orprecursor.

For purposes of the present invention, water vapor is defined as waterin the gaseous form, and distinguished from small droplets of watercommonly called “mist.” Because mist is water that is condensed in theform of small droplets, there is essentially no net warming effect whenmist settles on a surface that would correspond to a heat ofvaporization. For purposes of the present invention, steam is vaporizedwater at or above the boiling point of water, which depends on thepressure, e.g. 100° C. if the pressure is 1 atmosphere. When steam isprovided at a temperature greater than the boiling point of water, is itcalled superheated steam. Water vapor optionally may be provided fromcompositions comprising components in addition to water, such asdissolved gasses such as ozone, or inert gasses such as nitrogen. It iscontemplated that water vapor may be supplied to the sulfuric acidcomposition in any manner, either essentially pure, or in compositions,either above, or below or at 100° C., and having pressures or partialpressures of water vapor either above, below or at 1 atm. The watervapor optionally may further comprise additional ingredients, such as anoxidizing agent as discussed above. Other ingredients, such assurfactants, cosolvents or the like, are additionally contemplated.

The present invention may be used in single wafer processingapplications where the wafers are either moving or fixed, or in batchapplications. Alternatively, the method of the present invention may beused to process multiple wafer-like objects simultaneously, as occurswith batches of wafers when being processed in a spray processing toolsuch as the MERCURY® or ZETA® spray processors commercially availablefrom FSI International, Inc., Chaska, Minn., or the Magellan® system,also commercially available from FSI International, Inc., Chaska, Minn.

In an embodiment of the present invention, it has been found that theeffectiveness and efficiency of removal of materials from the surface ofa substrate is particularly enhanced wherein the liquid sulfuric acidcomposition has a water/sulfuric acid molar ratio of no greater thanabout 3:1, or no greater than about 2:1. In a preferred embodiment ofthe present invention, it has been found that the effectiveness andefficiency of removal of materials from the surface of a substrate isparticularly enhanced wherein the liquid sulfuric acid compositionhaving a water/sulfuric acid molar ratio of no greater than about 1:2.In an embodiment of the invention, the liquid sulfuric acid compositiondoes not contain water. For ease in obtaining materials, however, anembodiment of the invention contemplates that the liquid sulfuric acidcomposition will contain at least as much water as is conventionallypresent in the raw materials. In another embodiment of the presentinvention, the liquid sulfuric acid composition has a water/sulfuricacid molar ratio of from about 1:2 to about 1:4.

Stated another way, preferably the liquid sulfuric acid has aconcentration by volume greater than about 50 vol %, more preferablygreater than 80 vol %, and most preferably greater than 90 vol %. Forpurposes of the present invention, when volume ratios of sulfuric acidare discussed, it is intended that the content of sulfuric acid iscalculated based on 96 Wt % sulfuric acid source. Thus, a sulfuricacid/water composition comprising sulfuric acid in a content of 50% byvolume comprises 50 vol % of 96 Wt % sulfuric acid and 50 vol % water.

Preferably, the substrate is heated to a temperature of at least about90° C. either before, during or after dispensing of the liquid sulfuricacid composition. The liquid sulfuric acid composition is exposed towater vapor in an amount effective to increase the temperature of theliquid sulfuric acid composition on the substrate surface above thetemperature of the liquid sulfuric acid composition prior to exposure tothe water vapor. In an embodiment of the present invention, the liquidsulfuric acid composition is exposed to water vapor in an amounteffective to increase the temperature of the liquid sulfuric acidcomposition on the substrate surface above both (i) the temperature ofthe on-substrate liquid sulfuric acid composition prior to exposure tothe water vapor and (ii) the temperature of the water vapor. Eitherafter or between steps of the above described treatment, the substrateis preferably rinsed.

It has been found that the amount of water present in the liquidsulfuric acid composition prior to or as applied to the substrate isimportant to the effectiveness of the removal of undesired material.Specifically, it has been found that sulfuric acid compositions thatinitially contain too much water are less able to strip resist whenexposed to water vapor. While not being bound by theory, it is believedthat these diluted sulfuric acid compositions are either less able totake up water vapor in an amount effective to increase the temperatureof the liquid sulfuric acid composition above the temperature of theliquid sulfuric acid composition prior to exposure to the water vapor,or the chemical activity of the composition is decreased by the water,or both.

In embodiments where the substrate is at an ambient processingtemperature below the boiling point of water (particularly in atemperature range of about 20-60° C.), the temperature of the liquidsulfuric acid composition is substantially increased upon addition ofwater vapor. Surprisingly, it further has been found that even when thesubstrate and/or the sulfuric acid composition is at a high temperature(e.g. greater than about 90° C.), and particularly at a temperature ator above 100° C., the water vapor is taken up by the liquid sulfuricacid composition even though the temperature of the liquid sulfuric acidcomposition is near or above the boiling point of water. While not beingbound by theory, it is believed that the liquid sulfuric acid has adesiccating effect, thereby causing water from the water vapor to becondensed into the liquid sulfuric acid composition and releasing theenergy corresponding roughly to the heat of vaporization stored in thewater vapor.

In one embodiment of the present invention, the substrate is pretreatedwith a pretreatment liquid, such as an acid pretreatment, surfactant orsolvent, that acts to modify the surface characteristics of thesubstrate as desired.

As noted above, in an aspect of the present invention water vapor and/ornitrogen gas is additionally introduced into the treatment chamber toenvelop the substrate with a water vapor and/or a optionally nitrogengas environment during the treatment steps b) and c). While not beingbound by theory, it is believed that, in the case of the addition ofwater vapor, this enveloping step increases the amount of heat and wateravailable for interaction with the treatment chemicals. It has beenobserved that addition of water vapor in this manner in particularenhances the etching at the edge of the substrate.

Additionally, while not being bound by theory, it is believed that, inthe case of the addition of nitrogen, this enveloping step excludesatmospheric components that may adversely interact with the treatmentchemicals. It has been observed that addition of nitrogen gas in thismanner in particular enhances the etching at the center of thesubstrate. Methods wherein both water vapor and nitrogen gas areintroduced into the treatment chamber to envelop the substrate thus canadvantageously provide a process with uniform treatment profiles. In anaspect of the present invention, substantially all of the gas present inthe treatment chamber is nitrogen gas. In another aspect of the presentinvention, substantially all of the gas present in the treatment chamberis water vapor-containing nitrogen gas.

Preferably the water vapor of the envelopment is introduced so that itis exposed to the substrate at a water vapor temperature of from about70° C. to about 160° C. More preferably, the water vapor of theenvelopment is introduced so that it is exposed to the substrate at awater vapor temperature of from about 100° C. to about 150° C. In aparticularly advantageous embodiment, the water vapor of the envelopmentis introduced so that it is exposed to the substrate at a water vaportemperature of from about 120° C. to about 140° C.

In an embodiment of this invention, an SCl composition (1:1:10 hot SCl)is atomized by impinging the liquid stream of SCl solution with steam,and the substrate being treated is simultaneously enveloped in watervapor. This combination of steam impingement with simultaneouslyenveloping of the substrate being treated with water vapor can providean increase of the etch rate to 5 angstroms/min (approximately a 4×improvement over the best known commercially available method).

In another aspect of this embodiment, the substrate being treated issimultaneously enveloped in both water vapor and N₂. The combination ofthese components in the envelopment provides surprisingly uniform etchprofiles over the lateral dimension of the substrate, from edge tocenter.

The treatment of substrates with an SCl composition that is atomized byimpinging the liquid stream of SCl solution with steam while thesubstrate is simultaneously enveloped in water vapor and/or N₂ isparticularly advantageous for removal of dopants that are applied tosubstrates by plasma doping.

With reference to the figures, wherein like numerals are used to labellike components throughout the several figures:

FIG. 1 shows the resulting temperature when 20° C. H₂SO₄(96 Wt %) ismixed with 20° C. liquid water or 20° C. H₂O₂(30 wt %) in a rapidlystirred beaker. In region A, at H₂SO₄ volume fractions betweenapproximately 100% and 57%, the H₂SO₄/water blend increases intemperature with increasing water content. In region B, at fractionsbetween approximately 56% and 36%, the H₂SO₄/water blend decreasesslowly in temperature with increasing water content. In region C, atfractions between approximately 35% and 10%, the temperature of theblend decreases rapidly with increasing water content. The temperatureprofile of H₂SO₄ mixed with H₂O₂ follows the same trend, but with aslightly lower maximum temperature. A maximum temperature rise ofapproximately 110° (130° C. final temperature) is obtained with anH₂SO₄/water blend that is a blend of approximately 57 vol % H₂SO₄ and 43vol % H₂O₂. Also shown on the top axis is the H₂O to H₂SO₄ mole ratio ofthe water:H₂SO₄ blend. The boundaries between regions A and B isapproximately 2:1 water:H₂SO₄, and between B and C is approximately 5:1.

FIG. 2 shows the derivative of the water-added curve from FIG. 1. Thisshows the rise in temperature for each percent increase in water contentas a function of the fraction of H₂SO₄ in the solution. There is analmost linear decrease in dT/dWater from 100% to 37% H₂SO₄ fraction.While not being bound by theory, it is believed that the temperatureincrease of the solution (the heat of mixing) is being caused by theheat of hydration as water molecules coordinate around each sulfuricacid molecule. In the present invention, this strong attraction betweenthe water and sulfuric molecules drives the desiccant action that drawswater vapor from the atmosphere and into the sulfuric acid composition,even when the temperature of the sulfuric acid composition is above theboiling point of water. At approximately 55 vol % sulfuric acid, theheat of hydration is balanced by the thermal load of the added water,and additional added water has a net cooling effect on the blend. Atapproximately 37 vol % H₂SO₄, the hydration of H₂SO₄ appears to becomplete. As shown in the upper x-axis of FIGS. 1 and 2 show the moleratio of water:H₂SO₄ in the solution. The hydration appears to becomplete when approximately 5 moles of water are present for each moleof H₂SO₄.

In contrast to FIG. 1, the present invention adds water to the sulfuricacid composition by condensation of water vapor into the composition.This results in the heating of the composition not only by the heat ofmixing between H₂SO₄ and H₂O, but also by the water's heat ofvaporization that is regained when the water condenses into the sulfuricacid composition. Compared to adding liquid water to H₂SO₄, the thermalcontribution from water vapor's heat of vaporization allows largertemperature increases for a given amount of dilution.

FIG. 3 shows a modified spray processing system 10 for carrying out thepresent invention. In system 10, wafer 13, as a particularmicroelectronic device for example, is supported on a rotatable chuck 14that is driven by a spin motor 15. This portion of system 10 correspondsto a conventional spray processor device. Spray processors havegenerally been known, and provide an ability to remove liquids withcentrifugal force by spinning or rotating the wafer(s) on a turntable orcarousel, either about their own axis or about a common axis. Exemplaryspray processor machines suitable for adaptation in accordance with thepresent invention are described in U.S. Pat. Nos. 6,406,551 and6,488,272, which are fully incorporated herein by reference in theirentireties. Spray processor type machines are available from FSIInternational, Inc. of Chaska, Minn., e.g., under one or more of thetrade designations MERCURY® or ZETA®. Another example of a single-waferspray processor system suitable for adaptation in accordance with thepresent invention is available from SEZ AG, Villach, Austria and soldunder the trade designation SEZ 323. Another example of a tool systemsuitable for adaptation in accordance with the present invention isdescribed in U.S. patent application Ser. No. 11/376,996, entitledBARRIER STRUCTURE AND NOZZLE DEVICE FOR USE IN TOOLS USED TO PROCESSMICROELECTRONIC WORKPIECES WITH ONE OR MORE TREATMENT FLUIDS, filed onMar. 15, 2006; or as described in U.S. Patent Application PublicationNo. 2005/0205115.

Wafers 13 have been coated with an organic material that is to beremoved. In preferred embodiments, the organic material is photoresistmaterial. Organic materials that are challenging to remove includephotoresist that has been baked on by exposure to heat during previouswafer processing steps. Organic materials that are particularlychallenging to remove are those that have been heavily ion implantedduring previous wafer processing steps. The methods of the presentinvention are particularly and surprisingly effective in the removal ofheavily ion implanted photoresist materials.

Spray bar 20 comprises a plurality of nozzles to direct liquid aerosoldroplets onto wafer 13. Liquid sulfuric acid composition is providedfrom liquid supply reservoir 22 through line 23, and the stream of watervapor is similarly provided from supply reservoir 24 though line 25.Hydrogen peroxide is provided from peroxide supply reservoir 26 throughline 27 to sulfuric acid supply line 23. This configuration permitsaddition of peroxide to the sulfuric acid composition with the benefitthat the peroxide is not stored and heated in the presence of sulfuricacid, and additionally that the amount of peroxide used in the treatmentmethod may be independently controlled from the amount of sulfuric acidas dictated by specific process requirements. Thus, a variable peroxideconcentration can be applied during a treatment process as desired.Alternatively, the hydrogen peroxide can be supplied to the stream ofwater vapor at line 25. Spray bar 20 is preferably provided with aplurality of nozzles to generate aerosol droplets of treatmentcomposition that results from impinging the stream of a liquid sulfuricacid composition with the stream of water vapor. In a preferredembodiment, nozzles are provided at a spacing of about 3.5 mm in spraybar 20 at locations corresponding to either the radius of the wafer orthe full diameter of the wafer when spray bar 20 is in position overwafer 13. Nozzles may optionally be provided at different spacing closerto the axis of rotation as compared to the spacing of the nozzles at theouter edge of the wafer. A preferred spray bar configuration isdescribed in U.S. Patent Application Ser. No. 60/819,133, entitled“BARRIER STRUCTURE AND NOZZLE DEVICE FOR USE IN TOOLS USED TO PROCESSMICROELECTRONIC WORKPIECES WITH ONE OR MORE TREATMENT FLUIDS”, filed onJul. 7, 2006.

Preferably, the liquid sulfuric acid composition has a water/sulfuricacid molar ratio of no greater than about 5:1. Thus, the liquid sulfuricacid composition is limited in water content. In one embodiment, theliquid sulfuric acid composition may comprise a solvent that does notsubstantially interfere with the coordination of subsequently addedwater vapor with sulfuric acid, as discussed in more detail herein.Preferred such solvents are inert with respect to the substrate to betreated (e.g. the wafer), such as fluorine-based liquids. An example ofsuch inert solvents include the Fluorinert™ solvents commerciallyavailable from 3M, St. Paul, Minn. It should be noted that theabove-mentioned molar ratio recites the water/sulfuric acid molar ratio,and not the solvent/sulfuric acid ratio. This underscores that thesolvent that does not substantially interfere with the coordination ofsubsequently added water vapor with sulfuric acid does not factor intothis ratio of the present inventive embodiment.

More preferably, the liquid sulfuric acid composition is highlyconcentrated. Preferably, the liquid sulfuric acid composition isdispensed at a sulfuric acid concentration of at least about 80 vol %,more preferably at least about 90 vol %, and most preferably at leastabout 94 vol %. As shown in FIGS. 1 and 2, these high H₂SO₄concentrations result in the largest temperature rise per unit of watervapor condensed into the H₂SO₄ composition.

In an embodiment of the present invention, the liquid sulfuric acidcomposition comprises hydrogen peroxide. The hydrogen peroxide serves asan oxidant that assists in breaking down organic species to CO₂ andwater. Hydrogen peroxide is conveniently provided in a water-containingsolution blended with concentrated sulfuric acid to provide a liquidsulfuric acid composition having water/sulfuric acid molar ratio of nogreater than about 5:1. Advantageously, mixing of concentrated sulfuricacid with a water-containing hydrogen peroxide solution generates heatby an exothermic reaction, and so the resulting liquid sulfuric acidcomposition comprising hydrogen peroxide can be provided at elevatedtemperature while using less energy from a dedicated heat source to heatthe composition. This exothermic reaction is normally a significantsource of heat for the composition. However, in the present inventionthe reaction between the sulfuric acid composition and water vaporprovides the desired heat, and excess additions of water-based hydrogenperoxide can inhibit this sulfuric-vapor reaction. Therefore, with theknowledge of the effect of vapor in concentrated sulfuric acidcompositions as described herein, the skilled artisan can now adjust theH₂O₂ concentration to simultaneously optimize the heat generated by theH₂SO₄-vapor reaction while supplying sufficient reactants to oxidizeorganics.

In an aspect of the present invention, an oxidizing agent can beintroduced into the treatment chamber before, during or after dispenseof the liquid sulfuric acid composition.

For example, hydrogen peroxide can be mixed with the liquid concentratedsulfuric acid prior to introduction of the liquid sulfuric acidcomposition into the treatment chamber, or alternatively during or afterdispense of the liquid sulfuric acid composition in the treatmentchamber. Mixing of the hydrogen peroxide with the liquid concentratedsulfuric acid can be accomplished by the use of static mixers or activemixing techniques, or can be merely contacting one solution with theother, with mixing being accomplished by mere diffusion. Other agents,such as ozone, may be similarly incorporated in the liquid sulfuric acidcomposition as desired. Water-free oxidants such as ozone may besuperior to H₂O₂ as they will not dilute the H₂SO₄ composition. Forexample, oxidants other than H₂O₂ may be utilized in the inventivesulfuric-vapor process. For instance, ozone, nitric acid, the chromateion (Cr⁺⁶), or the eerie ion (Ce⁺⁴) may be incorporated in the processas described herein. In particular, these species might be added toH₂SO₄ in an anhydrous form, so that the H₂SO₄ remains relativelyundiluted. Other oxidants may also be used.

Preferably, the liquid sulfuric acid composition is dispensed at atemperature of at least about 90° C., and more preferably from aboutfrom about 90° C. to about 150° C. In another embodiment, the liquidsulfuric acid composition is preferably dispensed at a temperature offrom about 95° C. to about 120° C. In another embodiment, the liquidsulfuric acid composition is dispensed at a temperature of at leastabout 130° C. prior to exposure to the water vapor, and more preferablyfrom about 130° C. to about 200° C.

In one embodiment, wafer 13 is provided at a temperature below theboiling point of water, such as at a temperature of from about 20 toabout 60° C. Wafer 13 is preferably heated to a temperature of at leastabout 90° C., either before, during or after dispensing of the liquidsulfuric acid composition. More preferably, wafer 13 is heated to atemperature of from about 90° C. to about 150° C. In another embodiment,the wafers are heated to a temperature of from about 95° C. to about120° C. This heating can be carried out, for example, by heating thechamber using radiant heat, introduction of hot water or other liquidsolution to the wafer with substantial removal of the heated liquidprior to application of the concentrated sulfuric acid composition,introduction of heated gases to the chamber, and the like. If a liquidis used to heat the wafer by direct contact to the wafer, sufficientamount of the liquid is removed from the wafers prior to introduction ofthe concentrated sulfuric acid composition so that the concentratedsulfuric acid composition maintains the desired level of sulfuric acidconcentration prior to the exposure of the liquid sulfuric acidcomposition to water vapor.

In one embodiment of the present invention, the wafers can be preheatedby submerging one or more wafers into a heated bath of liquid, quicklydraining the contents of the bath (e.g. a “quickdump” procedure) andconducting the remaining treatment steps as described below. The bathliquid can be, for example, DI water, DI water containing sulfuric acid,sulfuric acid/hydrogen peroxide mixture, an inert fluid (such as afluorocarbon), sulfuric acid/ozone mixture, and the like. Thisembodiment can provide substantial benefit in enhancing throughput ofthe treatment process by more efficiently heating the wafers. An exampleof a particularly suitable process system that can be used to employthis embodiment is the Magellan® system commercially available from FSIInternational, Inc., Chaska, Minn.,

Preferably, the water vapor is introduced so that it is exposed to thewafers at a water vapor temperature of from about 70° C. to about 160°C. More preferably, the water vapor is introduced so that it is exposedto the wafers at a water vapor temperature of from about 100° C. toabout 150° C. In a particularly advantageous embodiment, the water vaporis introduced so that it is exposed to the wafers at a water vaportemperature of from about 120° C. to about 140° C. In a differentadvantageous embodiment, the water vapor is introduced so that it isexposed to the wafers at a water vapor temperature of about 130° C. Thisembodiment is relatively easy to carry out by boiling water underconventional conditions to form steam either inside or outside thetreatment vessel by conventional steam forming apparatus.

In another embodiment, the water vapor is provided at a temperaturegreater than the temperature of the liquid sulfuric acid compositionprior to exposure to the water vapor. This embodiment provides thebenefit of direct heating of the liquid sulfuric acid composition bydirect heat transfer, as well as the transfer of energy uponcondensation of the water vapor into the liquid sulfuric acid asdiscussed above. In an embodiment, the water vapor is provided at atemperature greater than about 150° C. for this purpose.

Optionally, the water vapor can additionally comprise another agent,such as hydrogen peroxide, nitric acid or ozone, as desired.

The water vapor is introduced into the treatment chamber in an amounteffective to increase the temperature of the liquid sulfuric acidcomposition above the temperature of the liquid sulfuric acidcomposition prior to exposure to the water vapor, and preferablyadditionally above the temperature of the water vapor. In an embodimentof the present invention, the liquid sulfuric acid composition isexposed to water vapor in an amount effective to increase thetemperature of the liquid sulfuric acid composition on the substratesurface above both (i) the temperature of the on-substrate liquidsulfuric acid composition prior to exposure to the water vapor and (ii)the temperature of the water vapor. Surprisingly, even when thetemperature of the liquid sulfuric acid composition is near or evenabove the boiling point of water, the water vapor still associates withthe liquid sulfuric acid composition in a manner to increase thetemperature of the liquid sulfuric acid composition, thereby enhancingthe organic material removing effectiveness of the increase thetemperature of the liquid sulfuric acid composition.

Preferably, sufficient liquid sulfuric acid composition and water vaporare present and mixed to increase the temperature of the liquid sulfuricacid composition by at least about 20° C., more preferably by at leastabout 40° C., and more preferably by at least about 60° C. This isparticularly significant since the liquid sulfuric acid composition isin place on the wafer, which itself acts as a heat sink and absorbssubstantial energy to maintain a temperature that is close to thetemperature of the liquid sulfuric acid composition. The temperature ofthe liquid sulfuric acid composition on the substrate surface can bedetermined by any appropriate measuring technique.

A cross-sectional view of a spray bar 30 is shown in FIG. 4,illustrating a preferred nozzle configuration of the present invention.In this configuration, liquid sulfuric acid composition orifices 32 and34 are directed inward to provide impinging streams 42 and 44. Watervapor dispense orifice 36 is located as shown in this embodiment betweenliquid sulfuric acid composition orifices 32 and 34, so water vaporstream 46 impinges with liquid sulfuric acid composition streams 42 and44. As a result of this impingement, atomization occurs, thereby formingliquid aerosol droplets 48. In addition, the droplets are given enhanceddirectional momentum toward the surface of the substrate because of therelatively high pressure of the water vapor stream as it exits fromwater vapor dispense orifice 36. This centrally located orifice in thenozzle assembly thus provides an advantageous directional aspect toassist in removal of material from the surface of the substrate.Alternatively, the positioning of the orifices may be reversed, i.e.,the liquid sulfuric acid composition may be dispensed from orifice 36and water vapor may be dispensed from orifices 32 and 34. For purposesof the present invention, a grouping of liquid orifices and gas orificesconfigured to provide streams that impinge with each other to form aliquid aerosol droplet stream or distribution is considered a nozzle.Optionally, an additional component, such as a gas, may be dispensedfrom one or more orifices in the nozzle assembly. In one embodiment,liquid dispense orifices have a diameter of from about 0.020 to about0.030 inch. In another embodiment, the liquid dispense orifices have adiameter of about 0.026 inch when located in the spray bar at a positioncorresponding to the center of the wafer to the mid radius of the wafer,and a diameter of about 0.026 inch from mid-radius of the wafer to theouter edge of the wafer. In an embodiment of the present invention,water vapor dispense orifices have a diameter of about 0.010 to about0.030 inch, preferably about 0.020 inch.

The location, direction of the streams and relative force of the streamsare selected to preferably provide a directional flow of the resultingliquid aerosol droplets, so that the droplets are directed to thesurface of a substrate to effect the desired treatment.

In one embodiment, the liquid aerosol droplets are caused to contact thesurface at an angle that is perpendicular to the surface of the wafer.In another embodiment, the liquid aerosol droplets are caused to contactthe surface of the wafer at an angle of from about 10 to less than 90degrees from the surface of the wafer. In another embodiment, the liquidaerosol droplets are caused to contact the surface of the wafer at anangle of from about 30 to about 60 degrees from the surface of thewafer. In a preferred embodiment, the wafer is spinning at a rate ofabout 250 to about 1000 RPMs during contact of the aerosol droplets withthe surface of the wafer. The direction of the contact of the dropletswith the wafer may in one embodiment be aligned with concentric circlesabout the axis of spin of the wafer, or in another embodiment may bepartially or completely oriented away from the axis of rotation of thewafer. System 10 preferably employs suitable control equipment (notshown) to monitor and/or control one or more of fluid flow, fluidpressure, fluid temperature, combinations of these, and the like toobtain the desired process parameters in carrying out the particularprocess objectives to be achieved.

FIG. 5 shows an example of a modified spray processing system 50 forcarrying out an aspect of the present invention, where liquid sulfuricacid composition is dispensed onto a portion of the substrate surfacethat is less than the entire surface of the substrate. In system 50,wafer 53, as a particular microelectronic device for example, issupported on a rotatable chuck 54 that is driven by a spin motor 55. Asabove in system 10, this portion of system 50 corresponds to aconventional spray processor device. Liquid sulfuric acid composition isprovided from liquid supply reservoir 62 through line 63 to dispenseorifice 70, which is configured to dispensing liquid sulfuric acidcomposition onto a portion of the substrate surface that is less thanthe entire surface of the substrate. This controlled dispense permitslocalized treatment of the desired portion of wafer 53. Hydrogenperoxide is provided from peroxide supply reservoir 66 through line 67to sulfuric acid supply line 63. This configuration permits addition ofperoxide to the sulfuric acid composition with the benefit that theperoxide is not stored and heated in the presence of sulfuric acid, andadditionally that the amount of peroxide used in the treatment methodmay be independently controlled from the amount of sulfuric acid asdictated by specific process requirements. Thus, a variable peroxideconcentration can be applied during a treatment process as desired. Astream of water vapor is similarly provided from supply reservoir 64though line 65 to dispense orifice 72. Alternatively, the hydrogenperoxide can be supplied to the stream of water vapor at line 65.Dispense orifices 70 and 72 may optionally be configured so that thestream of liquid sulfuric acid composition and the stream of water vaporat least partially intersect prior to impinging the surface of thesubstrate. Alternatively, dispense orifices 70 and 72 may optionally beconfigured so that the stream of liquid sulfuric acid composition andthe stream of water vapor at least partially intersect on the surface ofthe substrate, or so that the stream of water vapor impinges the streamof liquid sulfuric acid composition before the stream of liquid sulfuricacid composition impinges the substrate. In an embodiment of the presentinvention, the dispense orifices 70 and 72 are moved together during thetreatment to scan across the surface of the substrate. In an embodimentof the present invention, lines 65 and 67 can be linked to form a twoorifice nozzle array to assist in positioning control for scanningacross the surface of the substrate.

In an embodiment of the present invention, system 50 is configured sothat the substrate is rotating, and dispense orifices 70 and 72 arepositioned so that the stream of liquid sulfuric acid compositionimpinges the substrate at a point ahead of the point where the stream ofwater vapor impinges the substrate, relative to the rotational directionof the rotating substrate. Alternatively, system 50 may be configured sothat the stream of water vapor impinges the substrate at a point aheadof the point where the stream of liquid sulfuric acid compositionimpinges the substrate, relative to the rotational direction of therotating substrate.

In the embodiment wherein the liquid sulfuric acid composition isdispensed onto a portion of the substrate surface that is less than theentire surface of the substrate, water vapor may be generated in anothermanner that does not provide that the water vapor is in a stream thatimpinges either the substrate or the stream of liquid sulfuric acidcomposition. For example, heated DI water may be splashed down onto therotating turntable, thereby generating water vapor. Alternatively, watervapor can be generated inside the treatment chamber by any appropriatealternative water vapor generation technique, such as by heating and/oragitating water in the treatment chamber. In yet another alternative,the water vapor can be generated outside of the treatment chamber andintroduced to the treatment chamber in the desired water vapor form. Inone embodiment, water vapor could be produced by bubbling a gas (e.g.N₂) through a column of water (preferably hot water). In anotherembodiment, the gas could pass over the surface of a quantity of water.In another embodiment, the gas could pass through an irrigated packedcolumn as commonly used in chemical engineering. In another embodiment,substantially pure water vapor could be produced by boiling liquidwater. The gaseous products from any of these alternatives could befurther heated. Other embodiments are also possible.

The exposure of the liquid sulfuric acid composition to water vapor canbe carried out at any time effective to increase the temperature of theliquid sulfuric acid composition when in place on the organic materialcoated substrate. In one embodiment, water vapor is introduced to thetreatment chamber during the dispense of the liquid sulfuric acidcomposition. It will be appreciated that in this embodiment, thetemperature of the liquid sulfuric acid composition may begin toincrease even prior to contact of the composition with the substrate. Inthis embodiment, the increase of the temperature of the liquid sulfuricacid composition upon exposure to water vapor as discussed above can betaken to be the difference between the temperature of the liquidsulfuric acid composition at dispense and the maximum temperature of theliquid sulfuric acid composition after exposure to water vapor.

In another embodiment of the present invention, the liquid sulfuric acidcomposition is provided to the wafers not in a continuous stream, butrather in a plurality of discrete pulses. These pulses are preferablyshort (i.e. from about 3-10 seconds in length), and at high flow (i.e.at a flow rate of about 0.3-2 lpm). There preferably is a time period ofabout 5 to 20 seconds between pulses with no flow of liquid. Whenoperating with pulsed liquid flow, water vapor optionally is onlyintroduced during the pulse, reducing the amount of water vapor that isflushed from the chamber during the present process. Likewise, watervapor can be optionally introduced during the pulse, to enhance thetemperature rise of the sulfuric acid composition before its contactwith the substrate, or between pulses, to emphasize the heating of thecomposition while on the substrate. Alternatively, water vapor may becontinuously introduced to the chamber, with the liquid sulfuric acidcomposition being provided to the wafers in a plurality of discretepulses. In another embodiment, liquid sulfuric acid composition may becontinuously introduced to the chamber, with the water vapor beingprovided to the wafers in a plurality of discrete pulses.

Additional manipulation steps are also contemplated during the describedmethod, such as exposure of the substrate to megasonic energy before,during or after treatment by the liquid sulfuric acid composition.

It will be appreciated that the various embodiments of the method asdescribed herein (such as variation in delivery of the sulfuric acidcomposition) are not limited to use with the specific apparatus of thefigures, but rather are applicable to use in all configurations oftreatment machines appropriate for use in carrying out the presentlydescribed methods.

The principles of the present invention will now be described inconnection with the following illustrative examples.

Example 1 I. Experimental Techniques A. Sample Preparation

Wafer samples were prepared for evaluation of effectiveness of removalof ion implanted photoresist as follows:

-   -   200 mm diameter silicon wafers were coated with Shipley UV6 248        nm photo resist.    -   The photoresist coating on the wafers was then patterned using        conventional photoresist patterning techniques.    -   The patterned wafers were implanted with arsenic at an energy of        40 keV, and with a dose of either 5×10¹⁴ or 1×10¹⁵ atoms/cm²        (5E14 or 1E15).    -   In order to carry out certain tests, approximately 2×2 cm        fragments or “chips” were cleaved from patterned wafers for use        as samples.

B. On-Wafer Temperature Measurements

Measurements of the maximum on-wafer temperature were made by attachinglabels to wafers with dots that changed color irreversibly at specifiedelevated temperatures (TL-10 series from Omega Engineering, Stamford,Conn.). The labels were covered with a 0.7 mm glass sheet attached withhigh temperature epoxy for protection from the stripping chemistries.

C. Treatment Process

The wafers prepared in the manner described above were treated in asingle wafer spin spray processing tool wherein fluids are dispensedonto the wafer from a horizontal spray bar comprising an array ofnozzles extended above the wafer to provide a spray footprint that spansthe full radius of the wafer, so that as the wafer spins about itscenter, the full surface of the wafer is uniformly treated. The wafer tospray bar distance is about 1 inch and the wafer spinning speed is 300rpm.

The sulfuric acid/peroxide composition that is dispensed in each of theexamples is provided at a flowrate of 500 cc/min H₂SO₄+50 cc/min 30%H₂O₂. All processes preheat sulfuric acid to 150° C. before mixing withroom temperature 30% hydrogen peroxide.

Specific treatments were carried out under the following conditions:

Comparative Process 1—Baseline Process

In this process, hot sulfuric acid/hydrogen peroxide composition wasdispensed on a wafer through the above described spray bar, withoutsimultaneous introduction of water vapor.

In this process, the wafer was first preheated for 30 seconds bydirecting hot water onto the wafer. Excess water was then spun off ofthe wafer. Then a composition of sulfuric acid and hydrogen peroxide wasrun up to the spray bar but diverted to the drain in order to stabilizethe chemical flow. The sulfuric acid and hydrogen peroxide compositioncontinued to flow to drain for an addition 180 seconds while thetemperature of the sulfuric acid was increased and stabilized at 150° C.At this point the chemical composition was directed through the spraybar and onto the rotating wafer for predetermined dispense times rangingfrom 5 seconds to 300 seconds. Following the chemical dispense the waferwas rinsed with DI water and spun dry.

Comparative Process 2—Baseline Process With Bowl Steam

In this process, hot sulfuric acid/peroxide composition was dispensed ona wafer through the above described spray bar, with simultaneousintroduction of water vapor into the chamber by dispensing 95° C. hotwater into the bottom of the chamber bowl.

In this process, the wafer was first preheated for 30 seconds bydirecting hot water on the wafer. Excess water was then spun off of thewafer. 95° C. hot water was then dispensed into the bottom of thechamber bowl for 60 seconds to create water vapor. 95° C. hot watercontinued to be dispensed into the bottom of the chamber bowl for anadditional 60 seconds while a composition of sulfuric acid and hydrogenperoxide was run up to the spray bar but diverted to the drain in orderto stabilize the chemical flow. 95° C. hot water continued to bedispensed into the bottom of the chamber bowl and sulfuric acid andhydrogen peroxide composition continued to flow to drain for anadditional 180 seconds while the temperature of the sulfuric acid wasincreased and stabilized at 150° C. At this point, 95° C. hot watercontinued to be dispensed into the bottom of the chamber bowl while thechemical composition was directed through the spray bar and onto therotating wafer for predetermined dispense times ranging from 5 secondsto 300 seconds. Following the chemical dispense the wafer was rinsedwith DI water and spun dry.

Inventive Process—Chemical Mixture with Steam

In this process, hot sulfuric acid/peroxide composition was dispensed ona wafer through the above described spray bar, with simultaneousintroduction of water vapor in the chamber by directing steam through aseries of orifices in the spray bar, thereby causing the stream of steamto impinge the stream of hot sulfuric acid/peroxide composition, therebyatomizing the hot sulfuric acid/peroxide composition. The steam wasprovided at a pressure of 30 psig steam, a temperature of 131.2° C., anda steam flowrate of 160 lpm.

In this process, the wafer was first preheated for 90 seconds bydirecting steam through the spray bar and onto the wafer. Steamcontinued to be dispensed onto the wafer for an additional 60 secondswhile a composition of sulfuric acid and hydrogen peroxide was run up tothe spray bar but diverted to the drain in order to stabilize thechemical flow. Steam continued to be dispensed onto the wafer andsulfuric acid and hydrogen peroxide composition continued to flow todrain for an additional 300 seconds while the temperature of thesulfuric acid was increased and stabilized at 150° C. At this point,steam continued to be dispensed through the spray bar and onto the waferwhile the chemical composition was also directed through the spray barand onto the rotating wafer for predetermined dispense times rangingfrom 20 seconds to 90 seconds. Following the chemical dispense the waferwas rinsed with DI water and spun dry.

E. Temperature Analysis

The graph shown in FIG. 7 shows the wafer temperatures achieved bydispensing the sulfuric acid composition at the same temperature, butunder different conditions of co-dispense with water vapor. It was foundthat wafer temperatures were surprisingly much higher in a very shorttreatment period in the inventive system having impinging streams ofsulfuric acid composition with steam, as compared to a control with nowater vapor co-dispense, and with water vapor dispensed ambiently in thetreatment chamber. In the graph legend, comp-1 refers to ComparativeProcess 1, described about, comp-2 refers to Comparative Process 2,described above, and invent refers to Inventive Process, describedabove.

F. Resist Removal Evaluation

After treatment of wafers and wafer chips as indicated, removal ofresist and residues was evaluated by microscope inspection. The chemicaldispense time sufficient to provide removal of all resist and residuesin seconds is reported in the following Table I.

TABLE I Photoresist implant Photoresist implant conditions conditions 5× 10¹⁴ ions/cm² 1 × 10¹⁵ ions/cm² 40 keV, As 40 keV, As Comparativeprocess 1 80 >300 Comparative process 2 40 300 Invention 20 90

This data shows that the inventive process provides surprisingly rapidremoval of resist and residue as compared to a control with no watervapor co-dispense, and with water vapor dispensed ambiently in thetreatment chamber.

Example 2

Additional experiments were conducted to demonstrate the effectivenessenveloping the substrate with water vapor and/or nitrogen gas during thetreatment steps described above. In these experiments, oxide etch trialswith and without the use of methodologies of the present invention werecarried out. With the exception of the Control, oxide was etched from awafer using SC-1 solution for 60 seconds at a 70° C. dispensetemperature.

The results of these tests are graphically presented in FIG. 6.

Specifically, the lines on the graph show the following:

-   -   1) Control: Baseline process with no SCl dispense on the wafer.        This evaluation is performed to verify that the tool is        operating correctly and not inadvertently contributing to the        oxide etch.    -   2) Steam impinge, steam envelopment: The SC-1 stream is impinged        with steam, and the wafer additionally is enveloped with a steam        environment. This process produces the best overall oxide etch        rate, roughly 3× to 4× the rate of processes without steam.    -   3) Steam envelopment only: The SC-1 stream is not impinged, but        the wafer is enveloped with a steam environment. This process        produces an edge-fast oxide etch profile.    -   4) N₂ impinge, N₂ envelopment: The SC-1 stream is impinged with        N₂, and the wafer additionally is enveloped with a N₂        environment. This process produces a uniform etch profile with a        comparatively low oxide etch rate.    -   5) N₂ envelopment only: The SC-1 stream is not impinged, but the        wafer is enveloped with a N₂ environment. This process produces        a uniform etch profile with a comparatively low oxide etch rate.

All percentages and ratios used herein are volume percentages and volumeratios unless otherwise indicated. It will be understood that if thetreatment process is carried out at a different pressure, thetemperatures of the various components involved in the process can beadjusted accordingly. All publications, patents and patent documentscited are fully incorporated by reference herein, as though individuallyincorporated by reference. Numerous characteristics and advantages ofthe invention meant to be described by this document have been set forthin the foregoing description. It is to be understood, however, thatwhile particular forms or embodiments of the invention have beenillustrated, various modifications, including modifications to shape,and arrangement of parts, and the like, can be made without departingfrom the spirit and scope of the invention.

1. A method of treating a substrate, comprising a) placing a substratehaving material on a surface thereof in a treatment chamber; b)directing a stream of a liquid treatment composition to impinge thesubstrate surface; and c) directing a stream of water vapor to impingethe substrate surface and/or to impinge the liquid treatmentcomposition, wherein the stream of liquid treatment composition and thestream of water vapor originate from separate orifices and at leastpartially externally intersect prior to impinging the surface of thesubstrate, forming liquid aerosol droplets.
 2. The method of claim 1,wherein the water vapor is provided at a temperature of at least about100° C.
 3. The method of claim 1, wherein the water vapor is provided ata temperature of about 130° C.
 4. The method of claim 1, wherein thetreatment is removing a material, and the liquid treatment compositionis a liquid sulfuric acid composition comprising sulfuric acid and/orits desiccating species and precursors.
 5. The method of claim 1,wherein the liquid treatment composition is selected from the groupconsisting of the SC-1 composition (NH₄OH/Peroxide/Water), the SC-2composition (HCl/Peroxide/Water), the SPM composition (SulfuricAcid/Peroxide), SOM (sulfuric acid/ozone) composition, buffered oxideetch (HF and ammonium fluoride) compositions, and NH₄OH, H₃PO₄, HF, HClor HF/HCl compositions.
 6. The method of claim 1, wherein the stream ofliquid treatment composition and the stream of water vapor at leastpartially intersect prior to impinging the surface of the substrate. 7.The method of claim 1, wherein the stream of liquid treatmentcomposition and the stream of water vapor at least partially intersecton the surface of the substrate.
 8. The method of claim 1, wherein thestream of water vapor impinges the stream of liquid treatmentcomposition before the stream of liquid treatment composition impingesthe substrate.
 9. The method of claim 8, wherein the stream of liquidtreatment composition and the stream of water vapor are dispensed from anozzle construction comprising at least two orifices, the nozzleconstruction delivering a first stream of liquid treatment compositionand a second stream of water vapor in a manner to atomize the liquidtreatment composition before the liquid treatment composition impingesthe substrate.
 10. The method of claim 8, wherein the stream of liquidtreatment composition and the stream of water vapor are dispensed from anozzle construction comprising three orifices, the nozzle constructiondelivering a first stream of water vapor from a central orifice, and asecond stream and third stream of liquid treatment composition fromsecond and third opposing orifices in a manner to atomize the liquidtreatment composition before the liquid treatment composition impingesthe substrate.
 11. The method of claim 1, wherein the substrate isrotating, and the stream of liquid treatment composition impinges thesubstrate at a point ahead of the point where the stream of water vaporimpinges the substrate, relative to the rotational direction of therotating substrate.
 12. The method of claim 1, wherein the substrate isrotating, and the stream of water vapor impinges the substrate at apoint ahead of the point where the stream of liquid treatmentcomposition impinges the substrate, relative to the rotational directionof the rotating substrate.
 13. The method of claim 1, wherein the liquidtreatment composition at the time of exposure to water vapor has awater/sulfuric acid molar ratio of no greater than about 5:1.
 14. Themethod of claim 13, wherein the liquid treatment composition is exposedto the water vapor in an amount effective to increase the temperature ofthe liquid treatment composition above the temperature of both theliquid treatment composition and the water vapor prior to exposure tothe water vapor.
 15. The method of claim 1, wherein the stream of watervapor comprises an oxidizing agent.
 16. The method of claim 15, whereinthe oxidizing agent is hydrogen peroxide.
 17. The method of claim 15,wherein the oxidizing agent is nitric acid.
 18. The method of claim 1,additionally comprising introducing water vapor and/or nitrogen gas intothe treatment chamber to envelop the substrate with water vapor and/ornitrogen gas during the treatment steps b) and c).
 19. The method ofclaim 18, wherein water vapor is introduced into the treatment chamberto envelop the substrate with water vapor during the treatment steps b)and c).
 20. The method of claim 18, wherein substantially all of the gaspresent in the treatment chamber is nitrogen gas.
 21. The method ofclaim 18, wherein substantially all of the gas present in the treatmentchamber is water vapor-containing nitrogen gas.
 22. The method of claim19, wherein the water vapor of the envelopment is introduced so that itis exposed to the substrate at a water vapor temperature of from about100° C. to about 150° C.